1. Field of the Invention
The present invention relates to a semiconductor manufacturing apparatus for wafer processing, and positioning jig used for the same.
2. Description of Related Art
FIG. 6 is a cross section of the main components inside an etching chamber of a conventional etching apparatus (etcher). The hatching indicating the cross sectional plane is omitted in this drawing. FIG. 7 is a plan view illustrating the structure shown in FIG. 6, viewed from the top of a wafer 14. The cross section in FIG. 6 corresponds to a cross section along the I—I line in FIG. 7. The seat 22 shown in FIG. 6 is omitted in FIG. 7.
As shown in FIG. 6, a tapered recess 10a is formed in a flat susceptor 10. An opening 10b is formed in the middle at the bottom of this recess 10a, and an electrode 12 is provided inside this opening 10b. The upper part of the electrode 12 protrudes above the opening 10b. The upper surface of the electrode 12 is located lower than the upper surface of the susceptor 10. When the wafer 14 is placed on the electrode 12, the wafer 14 is surrounded by the surface of the recess 10a of the susceptor 10.
As shown in FIG. 7, a substantially cylindrical holder 18 is provided around the susceptor 10. A dozen or so wafer clamps 16 are disposed in-plane with this holder 18. Each of the wafer clamps 16 is fixed to the holder 18 by a wafer clamp fixing screw 20. The wafer clamps 16 protrude toward the center of the holder 18, and the distal ends thereof are bent downward in FIG. 6. As shown in FIG. 6, the holder 18 is fixed by holder fixing screws 24 to a seat 22 fixed on the inside of an etching chamber.
The above-mentioned susceptor 10 and electrode 12 are able to move up and down in FIG. 6. When the susceptor 10 and electrode 12 are moved upward in FIG. 6 in a state in which the wafer 14 has been placed on the electrode 12, the edges of the top surface of the wafer 14 come into contact with the distal ends of the wafer clamps 16. The wafer 14 is pressed from above by the wafer clamps 16, and as a result the wafer 14 is fixed to the electrode 12.
A hole 12a is formed in the center of the electrode 12, going from the top of the electrode 12 inward. The hole 12a extends up and down in FIG. 6. A wafer vertical chuck 26 is housed in this hole 12a in a state in which it is able to move in the direction in which the hole 12a extends.
The procedure for setting a wafer on the electrode will now be described through reference to FIG. 8. First, the susceptor 10 and electrode 12 are moved away from the seat 22, that is, downward in FIG. 8. The wafer 14 is conveyed by a wafer conveyance means (not shown) to the etching chamber, and brought over the electrode 12. The wafer vertical chuck 26 within the electrode 12 is then raised toward the wafer 14. The underside of the wafer 14 is vacuum chucked to the top of the wafer vertical chuck 26. After the wafer is chucked, the wafer vertical chuck 26 descends to its home position, and the wafer 14 is placed on the electrode 12. The susceptor 10 and electrode 12 are then raised until the upper surface of the wafer 14 comes into contact with the wafer clamps 16. As a result, the wafer 14 is fixed on the electrode 12.
However, when a wafer was placed on the electrode with a conventional device, because the conveyance precision of the wafer conveyance means was not very good, it was possible that the wafer would be set out of place from the specified position. If the wafer was brought into contact with the wafer clamps in this state, the pressure exerted on the wafer was uneven and the wafer would crack.
Also, the holder is removed from the seat during maintenance, and the wafer clamps must be positioned every time the holder is reinstalled. Accordingly, play is provided to the holes in which the wafer clamp fixing screws 20 are inserted (holes made in the wafer clamps 16) and to the holes in which the holder fixing screws 24 are inserted (holes made in the seat 22). In other words, the holes have diameters larger than those of the screws. This play is utilized to adjust the wafer clamps 16 so that they all come into contact at the proper location on the wafer. This adjustment is relatively difficult, though, and the wafer will still crack if there is even a little misalignment.
One object of the present invention is to provide a semiconductor manufacturing apparatus with which wafer placement can be performed with good positional precision in order to prevent wafer cracking.
A further object of the present invention is to provide a positioning jig that facilitates the positioning of the wafer clamp during maintenance.
Another object of the present invention is to provide a wafer-securing method.